Anal. Chem. 1004. 56.302-304
302
w
5). Water is undoubtably incorporated into the film as well during this process which renders the TCNQ film fully electroactive, thus permitting the redox equilibrium, via eq 7 or 8, to be established. These results also suggest the absence of “pinholes” in the virgin films for the transport of water to the platinum substrate. Registry No. Pt, 7440-06-4; Au, 7440-57-5; C, 7440-44-0; TCNQ, 1518-16-7; TCNQ-., 34507-61-4; 2,5-bis(oxyethanol)TCNQ-adipoyl chloride copolymer, 83462-96-8; 2,5-bis(oxyethano1)TCNQ-adipoyl chloride SRU,83462-97-9.
I
-0.2
2
4
6
8
IO
12
LITERATURE CITED
14
PH
Figure 1. pH response of (1) bare platinum electrode, (2)platinum electrode coated with a virgin TCNQ polymer film, and (3)platinum electrode coated with a TCNQ polymer film and cycled between +0.3 and -0.3 V vs. SCE. can be envisioned with the formation of surface platinum oxides via the following reactions:
+ H 2 0 + PtOH + H+ + ePtOH + PtO + H+ + eT C N Q + e- * TCNQPt + H2O + T C N Q * PtOH + TCNQ- + H+
(5)
+ H2O + 2TCNQ * PtO + 2TCNQ- + 2H+
(8)
Pt
(4)
(6)
(7)
or
Pt
(1) Cheek, G.; Wales, C. P.; Nowak, R. J. Anal. Chem. 1983, 55, 380. (2) Heineman, W. R.; Yacynych, A. M. Anal. Chem. 1980, 52, 345. ’ Day, R. W.; Inzeit, G.; Klnstie, J. F.; Chambers, J. Q. J. Am. Chem. SOC. 1982, 104, 6804. 1 Inzelt, G.; Day, R. W.; Kinstle, J. F.; Chambers, J. Q. J. Phys. Chem. 1983, 8 7 , 4592. Inzelt, G.; Day, R. W.; Kinstle, J. F.; Chambers, J. Q . J. Electroanel. Chem ., in press. Jacq J. Electrochim. Acta 1987, 12, 1345. Chambers, J. Q. I n “The Chemistry of Quinoid Compounds”; Patai, S., Ed.; Wlley: New York, 1974; Chapter 14. Laviron, E. J. Nectroanal. Chem. 1983, 146, 15. Inzelt, G.; Chambers, J. Q.; Day, R. W.; Klnstle, J. F., submitted for publication to J . Am. Chem . SOC Melby, L. R.; Harder, R. J.; Hertler, W. R.; Mahler, W.; Benson, R. E.; Mochel, W. E. J. Am. Chem. SOC. 1962, 8 4 , 3374. Boyd, R. H.; Phillips, W. D. J. Chem. Phys. 1965, 4 3 , 2927. Yamaglshi, A.; Sakamoto, M. Bull. Chem. SOC.Jpn. 1974, 47, 2152. Yamaglshl, A. Bull. Chem. SOC.Jpn. 1978, 4 9 , 1417. Lazorov, St.; Trlfonov, A,; Popov, Tz. 2.Phys. Chem, (Lelpzig) 1968, 238, 145. Hertler, W. R. J . Org. Chem. 1976, 41, 1412. Robinson, A. R.; Stokes, R. M. “Electrolyte Solutions”, 2nd ed.; Butterworths: London, 1959. Taken from “CRC Handbook of Chemistry and Physics”, 49th ed.; Weast, R. C., Ed.; The Chemical Rubber Co.: Cleveland, OH, 1968; pp D-78-80. Adams, R. N. “Electrochemistry at Solid Electrodes”; Marcel Dekker: New York, 1965. Chambers, C. A.; Chambers, J. Q. J. Am. Chem. SOC. 1966, 8 8 , 2922. Oilman, S . I n “Electroanalytlcal Chemistry”; Bard, A. J., Ed.; Marcel Dekker: New York, 1968; Vol. 2. Grubb, W. T.; King, L. M. AnalChem. 1980, 5 2 , 270.
.
Precedents for eq 4 and 5 are discussed by Gilman (19). The charge consumed by a typical TCNQ film electrode as determined by cyclic voltammetry or chronocoulometry is 0.3-3 mC cm-2; Le., (3.1-31) X mol cm-2. Since a platinum surface contains 1.3 X 1015atoms/cm2 or 2.2 X lo4 mol/cm2, there is sufficient reactant to reduce a reasonably thick TCNQ film assuming a surface roughness factor in the range 1-10. Gyorgy Inzelt I n this view the TCNQ polymer film acts as a n indicator of Department of Physical Chemistry and Radiology the platinum surface redox state. The large molar absorpL. Eotvos University tivities of TCNQ and TCNQ-. (10) and the facile charge Budapest, Hungary transport process operative for these electrodes (3-5) render James Q. Chambers* the TCNQ polymer ideal for this purpose. James F. Kinstle This explanation implies the penetration of water molecules Roger W. Day to the platinum substrate surface in the cycled and not in the Mark A. Lange virgin TCNQ film electrodes. Penetration of water is reaDepartment of Chemistry sonable since cyclic voltammetric response at cycled TCNQ University of Tennessee film electrodes is found for ions like Fe(CN)63-/4-,Br-/Br3-, Knoxville, Tennessee 37996-1600 and Fe(EDTA)-I2-. The Fe(CN)63-/4-couple appears ca. 0.2 V positive of the TCNQ wave and is attenuated in magnitude for review August 1, 1983. Accepted November 1, somewhat relative to the bare platinum response ( D F ~ ( c N ~ - RECEIVED 1983. This research was supported by the U.S. Army Research N 1 x lo4 cm2 s-l). Office (Project No. P-17715-c) and The University of TenThere is also compelling evidence that counterions are innessee. corporated into the film during the “breaking-in” process (3,
Laser Microprobe Mass Analysis of Refinery Source Emissions and Ambient Samples Sir: Particulate emissions from industrial plants, automobiles, and other sources have a significant impact on the quality of the environment. A typical ambient sample is made up of a collection of particles of differing morphologies from various sources. For both regulatory and environmental
reasons, it would be useful to have a procedure that can determine and quantitate the extent of contributions of various sources to an ambient sample. The major analytical problem involved in such an effort is to contend with the heterogeneity of the particulates that make up an ambient sample. A me-
0003-2700/84/0356-0302$01.50/00 1984 American Chemical Society
ANALYTICAL CHEMISTRY, VOL. 56, NO. 2, FEBRUARY 1984
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thod that can discriminate and chemically distinguish among particles in a heterogeneous collection of particles becomes necessary. Applications of laser microprobe mass spectrometry for analysis of urban aerosols ( I ) , particles deposited in human organs (Z),and asbestos fiber particles (3) have been reported. This paper reports on characterization of refinery emissions and ambient refinery samples. EXPERIMENTAL SECTION The laser mass spectrometry experiments were carried out on LAMMA-500 (manufactured by Leybold-Heraeus), which has been described in detail elsewhere ( 4 ) . With the aid of a microscope, the size, shape, and color of the particles were determined. Particles were then individually chosen, vaporized, and ionized with a Nd-YAG laser pulse (265 nm, 15 ns). The ions thus produced traverse a time of flight tube and are detected by an electron multiplier. Sample Description. (a)Source Samples. The source samples used in this study were obtained from two Exxon facilities, which we will refer to as refinery 1 and refinery 2. Refinery 1 uses a process to upgrade the heavier fractions of crude oil. Usually, metals and high molecular weight polar materials are concentrated in this fraction. The exhaust gases from this unit pass through a series of cyclones for particulate removal and finally are discharged into the atmosphere. Particles collected in the cyclones were used as source samples from this refinery unit. Refinery 2 produces gasoline and heating oil from gas oils. The cracking reactions are carried out catalytically. The flue gas from this unit is sent through a source assessment sampling system (SASS) which consists of a series of cyclones, a gas treatment section, sorbent trap, aqueous condensate collector, and a series of impingers. Particles collected in the cyclones were used as source samples for this refinery unit. (b)Ambient Samples. Ambient samples were obtained around both refinery 1and refinery 2 with high-volume air samplers. This type of sampler is recommended by the U.S. Environmental Protection Agency for total suspended particulates. The highvolume sampler collected particles with an aerodynamic diameter of less than 100 pm and typical collection times were of the order of 24 h. The samples were transferred onto a Formvar coated TEM grid by contacting the grid with the sample. Usually, such a procedure is sufficient to ensure enough particle transfer for the experiments to be carried out. Particles having nominal diameters of 1 to 5 pm were selected for these experiments. R E S U L T S AND DISCUSSION Model Compounds. The usefulness of laser mass spectrometry for the analysis of organic and inorganic compounds is well documented (5-8). Often, in particles of environmental interest, the organic and inorganic species are deposited on matrices. Two of the most commonly occurring matrices are carbonaceous materials and aluminosilicates. Both of these materials have characteristic laser mass spectra and can be readily identified. Carbonaceous matrices such as graphite, carbon black, and activated carbon contain a series of C,H, peaks (n = 1-20, m = 1, 5 ) in the positive and negative ion spectra. Aluminosilicates are distinguished by their negative ion mass spectra consisting of a series of peaks a t mlz 43 (AlO), 59 (AlOJ, 60 (Si02),76-77 (SO3,SiO,H), 103 (AlSiO,), 119 (A1Si04), 137 (Siz05H), 145 (Also4), 161 (A1305), 163 (A1Si205),179 (A1Si2O6),197 (Si307H),and 221 (A1,07H). Figure l a is a typical mass spectrum of amorphous silica particles (4-8 pm) that were mixed with aqueous solutions of metal nitrates and chlorides and heated to 300 “C in a furnace. All of the elements deposited on the silica were observed in the mass spectrum. The concentrations of the elements were in the range of a few hundred to a thousand parts per million. No direct quantitative correlations could be made between the intensities of the ions in the mass spectra and the concentrations of the doped elements. Polynuclear aromatic hydrocarbons were deposited on graphite and aluminosilicate particles from both solution and
L----25
-4 I
100 50
+
-2
150
MI2
Figure 1. (a) Positive ion mass spectrum for silica particles doped with elements. (b) Positive ion mass spectrum for 225 ppm phenanthrene deposited on coal fly ash particle.
“
d
7 I
LANTHANIDES
Figure 2. (a) Mass spectrum of emission from refinery 1. (b) Mass spectrum of emission from refinery 2. vapor phase. For concentrations of doped compounds greater than 200 ppm (solution concentrations), the signal due to the parent molecular ion peak could be reproducibly observed. Figure l b shows the mass spectrum of 225 ppm of phenanthrene doped on coal fly ash, the peak at m / z 178 being due to the parent molecular ion of phenanthrene. Laser powers of the order of 105-106 W/cm2 are necessary to discriminate against the mass spectra of the matrix. Source Emissions. The source particles obtained for this study were representative of the emissions from the specific refinery processes. The objectives of studying the source emission particles are 2-fold: (1)to obtain structural information about these emissions and (2) to establish, if possible, a mass spectral fingerprint pattern that would allow such particles to be identified in ambient air samples taken around the refinery. The particles collected at the refinery (refinery 1) which upgraded heavy residues were predominantly black particles. The mass spectra of these particles exhibited a carbonaceous “CnHm”series of peaks along with peaks at mlz 51 and 67 due to V+ and VO’. These emissions can therefore be described as vanadium-containing carbonaceous particles. Figure 2a is a typical positive ion mass spectrum obtained from such a particle. Particles collected at the other refinery (refinery 2) were from a fluid catalytic cracking unit and mostly consisted of opaque and glassy particles. The negative ion mass spectra of these particles exhibit an “Al,Si,O,” series of peaks, indicating an aluminosilicate matrix. The positive ion mass spectra of these particles had peaks corresponding to lanthanides (La, c e , Pr, and Nd) at m l z 139-150 and m l z 155-166 due to their oxides (Figure 2b). The emission from this refinery is best described as lanthanide-containing alu-
304
ANALYTICAL CHEMISTRY, VOL. 56, NO. 2, FEBRUARY 1984
_________________-___l______l___________------------------------------------
Table I. Major Constituents of Refinery Emission and Ambient Samples around Refinery refinery 1 ambient 1 refinery 2 carbonaceous with V
Al,Si,O, Na, K, Ca, Ba AI,Si,O, Na, K, Ca, Fe F%O, carbonaceous with Pb carbonaceous with V Carbonaceous with V and Pb
Al,Si,O,
with lanthanides
ambient 2
A1,SiyO, with Na, K, Ca, Ba A1,SiyO, with Pb A1,SiyO, with lanthanides Fe,O, carbonaceous carbonaceous with Pb CaCO, v205
Mo
-
LANTHANIDES
Figure 3.
Mass spectrum of ambient particle around refinery 2.
minosilicate particles. The other elements identified in the spectrum were Na, Fe, K, Ti, Mn, and Pb. The negative ion mass spectra have peaks a t masses mlz 64 and 96, 97 indicating the presence of SO, type species. The emissions from both these refineries have characteristic mass spectral fingerprints that would make it possible to identify these particles in the ambient atmosphere. The differences between the emissions are a reflection of the differing processes used in these two refineries. Ambient Samples. The major aims in studying the mass spectra of the ambient particles were to identify the different sources contributing to the sample as well as examine if particles emitted from the refinery could be observed in these samples. The types of particles that could be distinguished on all of the ambient samples were transparent particles, glassy particles, and black particles. One hundred particles from each ambient sample were chosen for the mass spectral study. Table I lists the various classes of particles that were observed based on their mass spectra. For ambient samples around both refineries, the bulk of the particles consisted of the transparent and glassy particles. These were aluminosilicate particles containing Na, K, Ca, and often Ba and represent the background contribution from soil and dust and act as diluent. Lead containing carbonaceous particles, typical of auto exhaust, were also a major constituent. High molecular weight peaks, typical of organic compounds with peaks at masses 165,178,221-222,243-245, and 261-263 were observed on these particles. A peak a t mass 165 was reported as a fragment ion of alkyl-substituted phenanthrenes (9). Detection of organic impurities adsorbed on asbestos fiber has also been reported (IO). Most important, however, was the identification of particles in the ambient air that were emitted from the refinery. Vanadium-containing carbonaceous particles were observed in the ambient samples around refinery 1, which are possibly originating from this source. Figure 3 is a mass spectrum of a particle found in the ambient sample around refinery 2 and can be identified as a lanthanide-containing aluminosilicate particle. The vanadium oxide particles observed around ref i e r y 2 also originate from some part of the refinery. Distinct
sources are responsible for the calcium carbonate particles, the iron oxide, and the molybdenum-containing particles. This study shows that it is possible to identify various source emissions in ambient samples by using laser mass spectrometry. Since the majority contribution to ambient samples are soil particles, only a particle-by-particle analysis, as done above, can give an idea about the !ource emissions.
ACKNOWLEDGMENT We thank J. R. Rhodes of Colmbia Scientific Industries, Austin, TX, for the metal-doped silica particles. Registry No. Na, 7440-23-5;K, 7440-09-7;Ca, 7440-70-2;Ba, 7440-39-3; Fe, 7439-89-6; Pb, 7439-92-1; V, 7440-62-2; Mo, 7439-98-7;phenanthrene, 85-01-8. LITERATURE CITED (1) Wieser, P.; Wurster, R.; Seiler, H. Atmos. Environ. 1980, 14, 485-492. (2) Kaufmann, R.; Hillenkamp, F.; Weqhsung, R.; Heinen, H. J.; Schurmann, M. Proceedings of Scanning Electron Microscopy Symposium, Washington, DC, 1979. (3) Kaufmann, R.; Wieser, P.; Wurster, R . Scanning Electron Microsc. 1980, 607. (4) Wechsung, R.; Hillenkamp, F.; Kaufmann, R.; Nitsche, R.; Vogt, H.. Microsc. Acta, Suppl. 1978, No. 2 , 611. (5) Denoyer, E.; VanGrieken, R.; Adams, F.; Natusch, D. Anal. Chem. 1982, 5 4 , 26A. (6) Conzemius, R. J.; Capallen, J. M. Znt. J . Mass Spectrom. Zon Phys. 1980, 3 4 , 197. (7) Dutta, P. K.; Talmi, Y. Anal. Chim. Acta 1981, 132, 111. (8) Helnen, H. J. Znt. J . Mass Spectrom. Ion Phys. 1981, 3 8 , 309 (9) Yu, M. L.; Hites, R. Anal. Chem.’l981, 53, 951. (IO) DeWaUe, J. K.; Vansant, E. F.; Van Espen, P.; Adams, F. C. Anal. Chem. 1983, 55, 671.
P. K. Dutta* Department of Chemistry The Ohio State University Columbus, Ohio 43210
D. C. Rigano R. A. Hofstader Exxon Research and Engineering Co. Linden, New Jersey 07036
Eric Denoyer D. F. S. Natusch Department of Chemistry Colorado State University Fort Collins, Colorado 80523 F. C. Adams Department of Chemistry Universitiare Instellung Antwerpen (UIA) B-2610 Wilrijk, Belgium RECEIVED for review June 6, 1983. Accepted November 1, 1983.
